Two-cycle internal-combustion engine



Jan. 2 l 1930.

W. B. CHAPMAN Two-CYCLE INTERNAL COMBUSTION ENGINE Filed May l, 1928 ^IN NTR e .M

f/mYk-ezm/Qw ATTORNEYS Patented dan. 2l, 1,930

WILLIAM B. CHAPMAN, F JACKSON HEIGHTS, 'NEW YORK Two-CYCLE INTERNAL-COMBUSTION' ENGINE Application tiled Hay 1, A1928.' Serial No. 274,209.

The invention relates to internal combustion engines, particularly of` thetwo cycle type,l wherein the difiiculty involvedl -in prop-er scavengingl the cylinder of burned I gases and admitting'a fresh charge, during the short period in the cycle of the engine which may be given up to the above operations, has largely impairedv the capacity, eliiciency and reliability of the tWo cycle engine.

One important object of the resent invention is to increase capacity and) efliciency by improving the scavenging and charge-admitting operations, particularly by producing gaseous currents within the cylinder which 16 will be symmetrical with regard to the space.

to be scavenged and charged, thereby insuring that all parts of the cylinder space Will be substantially uniformly and completely scavenged and refilled with a fresh charge, 20 and eddy currents o r deadpockets in the cylinder Will lbe avoided, the above operations being so carried out as to avoid undue heating either of the incoming charge or'the piston head. vi.

Further objects and advantages of the invention will be inpartobvious and in part specifically pointed out in the description hereinafter 'contained which, taken in conjunction With the accompanying drawings, discloses certain preferred embodiments of the invention; such embodiments,v however,

are to be considered merely as illustrative o f lits principles. l Inthe drawings- Fig. 1 is a centrallongitudinal section through the cylinder and-pistonof 4an en-..

gine constructed to ,operate in accordance with the invention, the sectionbeing taken on line 1-1 of Fig. 2. i

Fig. 2 is a transverse section on line 2--2 of Fig. 1.

Fig. 3 is a view similar to on line 3 3 of Fig. 2.-

Fig. 4 is a perspective view showing the piston head construction. Theinvention is illustrated as applied to an engine having a cylinder 1 and piston 2, a crank case 3 being shown (Fig. 3) as adapted to supply fresh gaseous charges through y passageways 4 to the inlet ports hereinafter described, in the man-ner usual with two cycle Fig. 1 but taken der the vthrou-gh the cylinder until they reach the engines. f Suitable inlet openings 5 for the crank case are indicatedV in dottedy lines in Fig. 3.

In accordance with the present invention I' provide the head portion of the piston with channels forthe gasesV entering and leaving thecylinder spacewhich direct these gases into streams passing longitudinally of the cylinder, one or more of-such streams passing longitudinally along the' cylinder Wall, and the other stream passing centrally through the cylinder, in the opposite direction, the channels being located exteriorly of the piston aslater describedto avoid overheating efects either upon the gases or the piston. i

In the illustrated form of the invention the incoming gases are conducted from passage- Ways 4 to inlet ports 6 in the cylinder wall and the' piston 2 is 'provided with a corresponding numbervof inlet channels 7- which direct the incoming gases into a plurality of streams passing along the cylinder Wall to- Ward its head, and so confined as to cause the streams to be restricted ,in cross sectional area and to travel at a sufficiently highvelocity l to penetrate through the old.` gaseous charge and reach the head end of the cylin`V der. The total inlet -channel cross lsectional area may be, for example, about one-twentieth' -the total cross sectional 4area of the exhaust channels hereinafter described.

' Afterwreaching the head end ofthe cylingases turn and pass back centrally pistonhead, vWhere they are directed byl exhaust channels 8 to a plurality of exhaust ports 9 in the cylinder Wall. v

I prefer to stagger the inlet-and Yexhaust ports 6 and 9 symmetrically around the cyl-v inder wall, which results in a construction of piston headl which is symmetrical about the longitudinalaxis of thepiston, and also a flow of gases through the cylinder which is symmetrical about said axis', which results in a more uniform scavenging action as Well as uniform refilling with a fresh charge.`

The channels 7 and 8 being located ente-1 riorl on the head portion of the piston, do not orm any covered pockets in the piston.

I have foundthat ifthe incoming gases be lcd through interior passageways in the piston, the explosion heats up the adjacent arts of the piston unduly and causes too muc 1 expansion of the gases as they enter the elyindcr space, and preignition if an explosive mixture is so admitted, while if the exhaust gases are led through covered passageways in the piston, the ad`acent walls of the piston also will be overlieated, particularly such parts of the walls as are interposed'between the passageways and the cylinder space proper, and are therefore subjected to heat on both their top and bottom surfaces.

I prefer also to locate the inlet and exhaust ports at substantially the same level in the cylinder wall, although as indicated in Fig. 3, the exhaust ports are made somewhat larger and open somewhat before the inlet pprts. As shown in Fig. 2, the cylinder may provided with an annular exhaust chamber 10 into which the exhaust ports 9 open, and the inlet ports may be led up from passageways 4 through the cylinder wall sectors 11 which are interposed between the exhaust ports. This feature of construction locates the inlet and exhaust passage# ways 7 and 8 of thev piston in substantially the same transverse planeacross the piston head, and enables a short piston head to be employed. It will also be noted that the channels 8 are adapted to divide the cylinder space into veral substantially distinct com artments w en the piston is near the hea end 'of the cylinder. This is of advantage in Diesel engines of either the two or four cycle type, larger sizes of this type' of engine bein now provided with multijet fuel injectlon to afford more uniform ignition., A piston as illustrated in Fig. 4 will provide four separate compartments disposed symmetrically about the longitudinall axis of they piston, into each of which fuel may be injected.

-The symmetrical arrangement of inlet and outlet ports above described is also advan-n tageous in engines of the Diesel type. The

great amount of heat developed in Diesel en.

nes when operated under high loads has eretofore caused unequal expansion of the metal in the engine due to the unbalanced arrangement of the inlet and exhaust ports. The symmetrical arrangement above described will produce substantially uniform expansion around the central axis of the cylinder, permitting the engine to operate safely at higher loads.

While a specific embodiment of the invention has been disclosed it will be obvious that many changes may be made therein without departing from its general features as set forth in the appended claims.

I claim:

1. A two cycle internal combustion engine cylinder, a piston working therein, said piston having u on its head surface a plurality of substantia y radially disposed ridges making substantially equal angles with each other, a plurality of intake channels located in the exterior of the piston respectively adjacent the ends of said ridges, and the surfaces of the cylinder lying between said ridges being shaped to provide exhaust channels of relatively large cross sectional area and leading from the central portion of the piston to its `periphery,said cylinder having inlet and exhaust ports adapted to communicate respectively with the inlet and exhaust channels.

2. A two cycle internal combustion engine cylinder, a plston working therein, said iston having u on its head surface a plura ity of substantia ly radially disposed ridges making substantially ergal angles with each other, a plurality of inta e channels located in the exterior of the piston respectively adjacent the ends of said ridges, and the surfaces of the cylinder lyin between said ridges being shaped to provi e exhaust channels of relatively large cross sectional area and leading from the central portion of the piston to its periphery, said cylinder having inlet and exhaust ports adapted to communicate respectively with the inlet and exhaust channels, said cylinder being provided with an annular exhaust passageway communicating respectively with said exhaust orts and an annular inlet passageway locate at a different level from saidpassageway communicating with said inlet ports at points between said exhaust orts and at substantially the same level as the atter.

3. In combination, a two cycle internal combustion engine, a piston working therein, said piston having inlet and exhaust channels both 'lying in its exterior surface adjacent the head end of the piston for directing the inlet and the exhaust gases, the inlet channels being peripherally disposed and the exhaust channels running substantially radially, said respective sets of channels being-stag ered around the periphery of the piston and icing substantially symmetrically arranged in such manner that each exhaust channel makes substantially equal angles with different exhaust channels disposed on opposite sides thereof, and with the respective inlet channels disposed substantially mid-way between each pair of adjacent exhaust channels.

In testimony that I claim the foregoing, I have hereunto set my hand this 24th day of April, 1928.

WILLIAM B. CHAPMAN. 

